Hi. Can someone please remind me if I need to fast before my thyroid blood test tomorrow (I remember about when I should/shouldn’t take my meds beforehand, but not the fasting bit. The earliest appt I could get was 10.00 am. I’m also having calcium and parathyroid checked.
Thank you
Spangle15
Eating can lower TSH, so if that is the test your GP uses to adjust your dose then it's important to have it as high as possible to avoid a reduction in dose of Levo. Also, coffee can affect TSH so it's advised to have only water before the test.
If you take B Complex or a biotin supplement have you left it off for 7 days?
I disagree!
Yes Jim, we all know that.
From Thriva lab
Generally, you don’t need to fast before doing a thyroid function test. However, not fasting is sometimes linked to a lower TSH level. This means your results might not pick up on mild (subclinical) hypothyroidism — where your TSH levels are only mildly elevated.
From verywellhealth.com/optimum-...
Studies have shown that early morning thyroid blood tests taken after overnight fasting translate to higher TSH levels compared to those taken later in the day with no fasting.
From getrealthyroid.com/what-are...
Studies have shown that early morning fasting causes higher TSH levels compared to tests taken in the afternoon on patients that did not fast. Since fasting affect TSH levels, fasting might make it difficult to diagnose subclinical hypothyroidism, as the condition is diagnosed by specifically looking at TSH levels.
From google.com/amp/s/www.careno...
Because fasting causes higher TSH levels, it can make it hard to properly diagnose hypothyroidism—which is diagnosed specifically by looking at TSH levels.
From theinvisiblehypothyroidism....
In terms of fasting, most doctors tell thyroid patients that it’s not necessary to fast before a blood test. However, researchers have found that after eating, our TSH level becomes suppressed.
This means that a high TSH could instead look much lower after eating, and borderline levels no longer borderline. As so many doctors use the TSH level to decide if a patient is adequately treated, or in need of more or less thyroid medication, this could result in patients having their thyroid medication wrongly altered, or even being told that their ‘borderline’ hypothyroidism is now ‘normal’, resulting in some thyroid patients being inadequately treated for their thyroid condition. All because they ate before their test.
Therefore, your TSH level is likely to be at its highest and most reflective of its underlying status, when tested after fasting, in the early morning.
Maybe bring this up with a different member next time, as I've asked you before.
I wasn’t picking on you and I tried to make my response brief so we don’t go over old ground, you just happened to be the one suggesting fasting.
The comments you quote are rehashes of rehashed comments originating from a discredited Indian study that took blood early morning, sent the subjects away for a leisurely breakfast and found that later in the day TSH was lower, as it always is. The breakfast was coincidental, when they repeated their study with half the subjects eating and half fasting they found no difference.
I didn’t want to get into repeating the evidence, hence my cryptic comment. It’s important to let it be known that the fasting hypothesis is disputed less becomes accepted as undisputed fact.
Jim
you just happened to be the one suggesting fasting.
And it's always my posts about this subject that you respond to in this way, never anyone else's and there are many of us who suggest an early morning fasting test if TSH is important. I remember once asking you why you hadn't picked up on it when Diogenes mentioned it but you said you didn't want to bother him!
Why don't you contact Thriva lab and challenge their advice then let us know what they say? I doubt that they have rehashed the discredited Indian study you mention.
I reply to the first post, I invariably forget who has posted what so this removes bias. The Thriva comment is equivocal, these companies usually get a junior to knock up some general comments as part of their marketing. I’d be happy to reconsider my view if you could point me to a single study that shows eating a moderate breakfast affects TSH. The links you posted refer to time of day, the theinvisiblehypothyroidism document specifically refers to the sloppy Indian study (these people don’t READ the studies they cite). To add insult to injury they say menstruation makes no difference, not my thing but time of month has a great effect on TSH.
I reply to the first post, I invariably forget who has posted what so this removes bias.
Maybe you should read the whole thread before you respond rather than just reply to the first post and mine wasn't the first post it was the first reply and you commented specifically on what I said.
The Thriva comment is equivocal, these companies usually get a junior to knock up some general comments as part of their marketing.
Prove it. Contact Thriva and challenge what they say on their website. Then let us know what they say.
I’d be happy to reconsider my view if you could point me to a single study that shows eating a moderate breakfast affects TSH.
Point us to studies that say eating doesn't affect TSH.
Should have written 'reply' not 'post'. Your reply was the first, followed by my brief reply soon after as shown in the time details.
Better things to do, contact Triva if you wish but my recommedation is to ignore marketing drivel. "However, not fasting is sometimes linked to a lower TSH level" doesn't commit to anything, just a vague statement issued to look informative.
We should seek out good evidence before making firm assertions. It's fine to use phrases like 'I think ...' if we are not sure but when making categoric statements we should at least look for evidence.
Here is the first sloppy study that kicked off this nonsense: ijem.in/temp/IndianJEndocrM... . They concluded "TSH levels showed a statistically significant decline postprandially in comparison to fasting values." Wow! Impressive, but take a look at the methods: "Phlebotomy was performed after an 8-12 hour overnight fast between 7:30-8:30 am for free T4 and TSH measurements and the patients returned 2 hours after breakfast for their samples to be rechecked between 10:30-11:00 am on the same day." As Homer Simpson would say "Doh!!!". They took the blood at different times of the day! That's why TSH was lower after breakfast, it was three hours later.
This team did a follow up study which those making money out of hypothyroid patients never mention: ijem.in/temp/IndianJEndocrM... . This time the team used two groups, one got fed and the other got none. They then compared how TSH changed in each group, the group that continued fasting and the group that got brekkie. There was no difference: "Difference between Delta 1 and Delta 2 was not statistically significant (P = 0.61)." The change in TSH was entirely due to time of day.
I'm happy to reconsider my view if anyone finds a study (just one to read please) that demonstrates that eating a typical breakfast has a statistically significant effect on TSH. Research gives evidence, blogs recycle prejudice.
Better things to do
Of course you have. You pull other people up and ask for them to give evidence but are not prepared to do it yourself. You obviously don't have any and are not prepared to back up what you say which makes a mockery of you saying
"We should seek out good evidence before making firm assertions"
I'm happy to reconsider my view if anyone finds a study (just one to read please) that demonstrates that eating a typical breakfast has a statistically significant effect on TSH. Research gives evidence, blogs recycle prejudice.
Likewise if you do the same. Oh, sorry, you have better things to do!
You cannot demand evidence from other people if you're not prepared to provide it for what you assert.
Did you overlook the evidence I just gave? The flawed and follow-on studies from the team that started the debate. It's in my reply above.
No I didn't overlook it but this is the only one you keep referring to. I'd like to see another one. You do so much research I'm sure you have come across a different one.
Way back when this started I looked at half a dozen or more, now tucked away somewhere. We drifting away from this post and there's no point in my presenting you with study after study if you don't like the results of the one I've given you. The follow on study was good enough for the team that made the original mistake it should be good enough for anyone else. As it stands my offer to look at one study to the contary stands. Beyond that I'm not prepared to discuss it futher in this post. I will respond to a separate post if you want to set one up, it's not fair to Spangle to take this any further here.
I don't want to discuss it with you at all but it's you that keeps commenting on my posts. Next time let's see if you start this discussion with a different member who states the same and there are plenty of them.
I've asked you before and I'll repeat it, I'd prefer it if you didn't respond to any of my posts.
That's fine I will respond to original posts briefly to the effect that fasting doesn't affect TSH to any extent rather than clicking on reply to your reply (which is usually the first one).
The offer to look at one study you may find stands, just pm me any time. (I'm aware of the Kamat study that finds a tiny difference when consuming a 1,000 calorie meal).
It's all wrong anyway?? weird. fasting and early morning do cause a RISE in TSH ..which will aid a diagnosis of hypothyroid (which means you have a high TSH above some arbitrary current threshold for you area) which is what you want if you are borderline and trying to get a diagnosis. Eating does raise T3 (assuming most are capable of converting T4 to T3) or some are still capable of producing some in you r thyroid gland. T3 naturally increases after eating to aid digestion ..hence feeling tired if a tad hypothyroid inclined especially after a large Xmas lunch as your body doesn't up the T3 and it gets all used up. So take you meds if you are concerned about being too high in T4 and T3 to make sure you are not overdoing it or swung to hyperthyroid ..and I'd say don't take them if you are borderline and want a diagnosis... that said the swing is not that great..but enough. You will not suddenly go over TSH of 100 (I do that but that is if I stop meds for a while!), usually it may mean a TSH of 4.5 instead of 3.5 or so.
TSH is higher early morning.
Fasting does not alter TSH. There's weak evidence that consuming a large fatty meal might have a small effect.
I've never seen a study that shows eating a meal increases serum fT3. Obesity raises TSH, so long term over-eating (not fasting) will increase fT3.
I hadn't intended to ressurect a debate, just point out there is a different view. If anyone can point to a study (maximum one!) that demonstrates fasting, as opposed to a normal breakfast, elevates TSH I will take a look at it. Some show a rise in TSH due to taking blood at different times. Ramadan fasting, often with a meal at 1am, shifts the body clock and can have a small effect.
It's crucial to look at studies and not blogs. Businesses selling blood tests, supplements, books, making revenue from advertising etc. tend to echo patient prejudices to butter them up and maximise profits, or offer vague advice that doesn't say anything meaningful.
My TSH is suppressed because I take T3. I’ve not been taking B complex or biotin.
Spangle15
My TSH is suppressed because I take T3.
If your doctor accepts that this happens when taking T3 and is fine with your suppressed TSH then it's fine and no need to fast.
NHS England Liothyronine guidelines July 2019 Note that it says test should be in morning BEFORE taking Levo thyroxine
Also to test vitamin D, folate, B12 and ferritin
sps.nhs.uk/wp-content/uploa...
“prior to morning medications”. i.e. before taking levothyroxine or liothyronine, assuming you don’t take them at nighttime.
The suggestion to reduce 50 mcg levothyroxine for 10 mcg liothyronine is completely wrong. These idiots don’t understand pharmacokinetics. In the blood T3 is four to five times as potent as T4 but this ratio does not apply to tablets. Levothyroxine and liothyronine have completely different pharmacokinetics, different absorption and different half lives. Hence, research shows liothyronine is about three times as potent as levothyroxine. The correct ratio is 3:1.
No tea or coffee just water and no thyroxine either
Best results are when fasting. My doctor told me I can take my thyroid meds with water and have black coffee (no cream or sugar) and to bring something with me to eat after the bloodwork.
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